Narrative:

In this situation, I, the copilot, was not flying. After the captain landed on runway 35R at denver stapleton airport, we were instructed to taxi on Z taxiway to D3, cross runway 25, 26R, and hold short of 26L on C taxiway. We were also asked to report the fire station. The controller advised we were not in sight due to falling snow. The taxiways and runways were snow covered and not plowed. It was difficult to identify runways and taxiways. The visibility appeared lower during taxi than the reported RVR of 5000 ft. Our last known position was when we reported the fire station. (See diagram on reverse side.) due to poor visibility, unfamiliarity of the airport, and the inability of ground control to give us progressive taxiing, the captain and I decided to count the number of runways we cross, and make sure we only cross 2 runways. We decided that this method was the best way to taxi because the runway and taxiway signs were difficult to see and interpret. Both of us were so caught up in counting the number of runways we had crossed, I ignored the runway identifier signs. We also didn't realize that one of the runways was small, and possibly unlit. Neither of us saw runway 25 when we crossed it. We then counted crossing 2 runways and turned onto what we thought was C taxiway. We in fact crossed 3 runways, and turned onto B taxiway. We never saw that relatively small runway 25, and subsequently crossed 3 runways instead of 2. I feel this situation could be prevented in the future if a pilot relies primarily on runway and taxiway signs to affirm his position instead of relying on counting runways and intxns he thinks he crossed. If one miscounts for some reason, the same situation we had could occur.

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Original NASA ASRS Text

Title: EMS FLC CLRED TO CROSS 2 RWYS AND HOLD AT THIRD. SNOW CONDITIONS, TWR UNABLE TO GIVE PROGRESSIVE. CROSSED 3 RWYS.

Narrative: IN THIS SITUATION, I, THE COPLT, WAS NOT FLYING. AFTER THE CAPT LANDED ON RWY 35R AT DENVER STAPLETON ARPT, WE WERE INSTRUCTED TO TAXI ON Z TAXIWAY TO D3, CROSS RWY 25, 26R, AND HOLD SHORT OF 26L ON C TAXIWAY. WE WERE ALSO ASKED TO RPT THE FIRE STATION. THE CTLR ADVISED WE WERE NOT IN SIGHT DUE TO FALLING SNOW. THE TAXIWAYS AND RWYS WERE SNOW COVERED AND NOT PLOWED. IT WAS DIFFICULT TO IDENT RWYS AND TAXIWAYS. THE VISIBILITY APPEARED LOWER DURING TAXI THAN THE RPTED RVR OF 5000 FT. OUR LAST KNOWN POS WAS WHEN WE RPTED THE FIRE STATION. (SEE DIAGRAM ON REVERSE SIDE.) DUE TO POOR VISIBILITY, UNFAMILIARITY OF THE ARPT, AND THE INABILITY OF GND CTL TO GIVE US PROGRESSIVE TAXIING, THE CAPT AND I DECIDED TO COUNT THE NUMBER OF RWYS WE CROSS, AND MAKE SURE WE ONLY CROSS 2 RWYS. WE DECIDED THAT THIS METHOD WAS THE BEST WAY TO TAXI BECAUSE THE RWY AND TAXIWAY SIGNS WERE DIFFICULT TO SEE AND INTERPRET. BOTH OF US WERE SO CAUGHT UP IN COUNTING THE NUMBER OF RWYS WE HAD CROSSED, I IGNORED THE RWY IDENTIFIER SIGNS. WE ALSO DIDN'T REALIZE THAT ONE OF THE RWYS WAS SMALL, AND POSSIBLY UNLIT. NEITHER OF US SAW RWY 25 WHEN WE CROSSED IT. WE THEN COUNTED XING 2 RWYS AND TURNED ONTO WHAT WE THOUGHT WAS C TAXIWAY. WE IN FACT CROSSED 3 RWYS, AND TURNED ONTO B TAXIWAY. WE NEVER SAW THAT RELATIVELY SMALL RWY 25, AND SUBSEQUENTLY CROSSED 3 RWYS INSTEAD OF 2. I FEEL THIS SITUATION COULD BE PREVENTED IN THE FUTURE IF A PLT RELIES PRIMARILY ON RWY AND TAXIWAY SIGNS TO AFFIRM HIS POS INSTEAD OF RELYING ON COUNTING RWYS AND INTXNS HE THINKS HE CROSSED. IF ONE MISCOUNTS FOR SOME REASON, THE SAME SITUATION WE HAD COULD OCCUR.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.